1. Field of the Disclosure
The present disclosure relates to a pixel structure and method of fabricating the same, and more particularly, to a pixel structure in which source electrode/drain electrode and oxide semiconductor channel layer are electrically connected through connection electrodes, and method of fabricating the same.
2. Description of the Related Art
Thin film transistor (TFT) device is a kind of semiconductor devices commonly used in various types of display devices, such as liquid crystal display (LCD) devices, organic light-emitting diode (OLED) display devices and electronic paper (E-paper). The electron mobility of thin film transistor device is crucial to its switching rate, and thus is critical to display quality.
According to different semiconductor materials applied in the thin film transistor device, the thin film transistor devices in current display industries may include amorphous silicon thin film transistor (a-Si TFT) device, polycrystalline silicon thin film transistor (poly-Si TFT) device, and oxide semiconductor thin film transistor device. The amorphous silicon thin film transistor device is not able to satisfy requirements of foreseeable high performance display devices because of its low electron mobility. The typical value of the electron mobility of amorphous silicon thin film transistor device is smaller than 1 cm2/Vs. The electron mobility of poly silicon thin film transistor device is much higher, which is about 100 cm2/Vs. However, because of process issues such as high process complexity and poor uniformity, which is mainly generated by crystallization processes applied to large size substrates, the poly silicon thin film transistor device is mainly applied in small size display device. The oxide semiconductor thin film transistor device is an emerging thin film transistor device, which can be applied for large size substrate without the above-mentioned uniformity issue because oxide semiconductor material is generally amorphous crystalline. In addition, oxide semiconductor material may be formed by diverse methods such as sputter depositing, spin-on coating, and inkjet printing. The electron mobility of oxide semiconductor thin film transistor device is generally 10 times larger than the electron mobility of amorphous silicon thin film transistor device. The typical value of the electron mobility of oxide semiconductor thin film transistor device is generally between 10 and 50 cm2/Vs. Therefore, the oxide semiconductor thin film transistor device is expected to fulfill the requirement of foreseeable high performance display devices.
In the oxide semiconductor thin film transistor device, the high contact resistance between the source electrode/drain electrode and the oxide semiconductor layer would reduce the efficiency regardless of its high electron mobility. Thus, it is necessary to reduce the contact resistance between the source electrode/drain electrode and the oxide semiconductor layer for the oxide semiconductor thin film transistor device.